It’s highly unusual for a moderate earthquake that occurred beneath the sea in the Bay of Bengal to be felt as far as Delhi and Uttar Pradesh, averred an expert.
Expressing surprise over reports that tremors were felt in Delhi and Uttar Pradesh during Wednesday night’s earthquake, R.K. Chadha, senior seismologist, National Geophysical Research Institute (NGRI), said: “It’s a big surprise for a six magnitude earthquake (on Richter scale) occurring in the Bay of Bengal to be felt at Delhi. It is definitely unusual.”
He said the depth of the earthquake was 45 km beneath the sea and that was the reason for the tremors to be felt from Bhubaneswar to Chennai.
It was basically an intra-plate (within the Indian plate) earthquake and the seismic effect of such a temblor would be felt all along the coast. He said the Bay of Bengal was seismically less active with small to moderate size earthquakes, unlike the Andaman-Nicobar-Sumatra subduction zone, which was seismically highly active.
Dr. Chadha said earthquakes measuring more than 8 magnitude on the Richter scale could occur in the subduction zone (where the Indian plate is going below the Burmese plate) and such temblors could also trigger tsunami depending on the earthquake mechanism.
In general, earthquakes in the Bay of Bengal were scattered and occur along strike-slip faults, which do not generate a tsunami because of horizontal movement along the fault.
He said the earthquakes along the inter-plate were higher in magnitude and also in numbers when compared to intra-plate earthquakes. Very few earthquakes of less than 5 magnitude on Richter scale had occurred in the past few decades in the Bay of Bengal, except in ‘90 Degrees East Ridge’, a seismically active area.
